8.2.1 Design Requirements

Table 8-1 lists the parameters for this typical application.

Table 8-1. Design Requirements

PARAMETER

VALUE

High-side supply voltage

3.3V or 5V

Low-side supply voltage

3.3V or 5V

Voltage drop across RSHUNT for a linear response

±250mV(maximum)

8.2.2 Detailed Design Procedure

In the Typical Application figure, the high-side power supply (VDD1) for the AMC0x00D is derived from the

floating power supply of the upper gate driver.

The floating ground reference (GND1) is derived from the end of the shunt resistor that is connected to the

negative input of the AMC0x00D (INN). If a four-pin shunt is used, the inputs of the AMC0x00D are connected to

the inner leads. GND1 is then connected to the outer lead on the INN-side of the shunt. To minimize offset and

improve accuracy, route the ground connection as a separate trace that connects directly to the shunt resistor.

Do not short GND1 to INN directly at the device input; see the Layout Example section for more details.

Use Ohm's Law to calculate the voltage drop across the shunt resistor (VSHUNT) for the desired measured

current:

VSHUNT = I × RSHUNT

(2)

Select a RSHUNT value to satisfy the following two conditions:

• First, the voltage drop caused by the nominal current range does not exceed the recommended differential

input voltage range of VSHUNT ≤ ±250mV.

• Secondly, the voltage drop caused by the maximum allowed overcurrent does not exceed the input voltage

that causes a clipping output. Keep VSHUNT ≤ VClipping.

8.2.2.1 Input Filter Design

Place a differential RC filter (R1, R2, C5) in front of the isolated amplifier to improve signal-to-noise performance

of the signal path. Design the input filter such that:

• The cutoff frequency of the filter is at least one order of magnitude lower than the sampling frequency

(20MHz) of the ΔΣ modulator

• The input bias current does not generate significant voltage drop across the DC impedance of the input filter

• The impedances measured from the analog inputs are equal

Place capacitors C6 and C7 to improve common-mode rejection at high frequencies (>1MHz) and to improve

offset voltage performance. For best performance, verify C6 matches the value of C7 and that both capacitors

are 10 to 20 times lower in value than C5. NP0-type capacitors offer low temperature drift and low voltage

coefficients, and are preferred for common-mode filtering.

For most applications, the structure shown in Figure 8-2 achieves excellent performance.

R2

10

R1 10

C5

10nF

C6

1nF

C7

1nF

VDD1

GND1

INP

INN

Figure 8-2. Input Filter

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AMC0200D, AMC0300D

SBASAR7A – SEPTEMBER 2025 – REVISED JUNE 2026

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